我正在尝试用 Java 加密和解密一条消息，但我总是遇到同样的错误:
java.security.InvalidKeyException: Key is too long for unwrapping
我正在尝试模拟从服务器向客户端发送加密消息。
第一步:客户端生成私钥和公钥。
2nd 客户端将公钥发送给服务器。
第三:服务器生成对称AES key 。
4t:服务器使用他的 AES key 加密他想发送给客户端的文本。
5e:服务端用从客户端收到的公钥加密AES key 。
6e:服务端将密文和加密后的AES key 发送给客户端。
7e:客户端用自己的私钥解密AES key 。
8e:客户端使用解密后的 AES key 解密从服务器接收到的文本。
public class Test {
private static SecretKey secretKey;
private static KeyPair keyPair;
private static final String STRINGTOENCRYPT = "This is a test";
private static String stringEncripted;
private static String keyEncripted;
public static final byte[] IV_PARAM = {0x00, 0x01, 0x02, 0x03,
0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B,
0x0C, 0x0D, 0x0E, 0x0F};
public static void main(String[] args) {
generateKeys();
}
private static void generateKeys() {
secretKey = generateSecretKey(128);
keyPair = generateKeyPair(512);
stringEncripted = encriptString(STRINGTOENCRYPT);
keyEncripted = encriptKey(keyPair.getPublic());
decryptString();
}
private static void decryptString() {
Cipher cipher = null;
Key keyDecrypted = null;
try {
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.UNWRAP_MODE, keyPair.getPrivate());
keyDecrypted = cipher.unwrap(keyEncripted.getBytes(), "AES", Cipher.SECRET_KEY);
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec iv = new IvParameterSpec(IV_PARAM);
cipher.init(Cipher.DECRYPT_MODE, keyDecrypted, iv);
byte[] stringDecryptedBytes = cipher.doFinal(stringEncripted.getBytes());
String stringDecrypted = new String(stringDecryptedBytes);
System.out.println(stringDecrypted);
} catch (Exception e) {
e.printStackTrace();
}
}
private static KeyPair generateKeyPair(int lenght) {
KeyPair keyPublicAndPrivate = null;
try {
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(lenght);
keyPublicAndPrivate = keyGen.genKeyPair();
} catch (Exception ex) {
ex.printStackTrace();
}
return keyPublicAndPrivate;
}
private static SecretKey generateSecretKey(int lenght) {
SecretKey sKey = null;
if ((lenght == 128) || (lenght == 192) || (lenght == 256)) {
try {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(lenght);
sKey = kgen.generateKey();
} catch (NoSuchAlgorithmException ex) {
ex.printStackTrace();
}
}
return sKey;
}
private static String encriptString(String stringtoencrypt) {
byte[] stringtoencryptBytes = stringtoencrypt.getBytes();
Cipher cipher = null;
String stringEncrypted = null;
try {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec iv = new IvParameterSpec(IV_PARAM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
byte[] stringEncryptedBytes = cipher.doFinal(stringtoencryptBytes);
stringEncrypted = new String(cipher.doFinal(stringtoencryptBytes), "UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return stringEncrypted;
}
private static String encriptKey(PublicKey aPublic) {
String keyEncryptedString = null;
try {
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.WRAP_MODE, aPublic);
byte[] keyEncriptedBytes = cipher.wrap(secretKey);
keyEncryptedString = new String(keyEncriptedBytes, "UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return keyEncryptedString;
}
}
知道为什么会这样吗？
最佳答案
问题是您不能假设 RSA 或 AES 加密产生的字节代表字符串。当您使用 new String 生成字符串时，它会自动删除所有不代表字符的字节。如果您想拥有更多控制权并抛出异常(这应该是默认设置)，您可以使用 CharsetDecoder。
问题是，当您重新转换为字节时，某些字节可能会丢失。这意味着数字可能会小得多，这将以某种方式抛出异常，因为 unwrap 的输入现在太小了。
以下是一些说明如何使其正常工作的更改。我刚刚注释掉了您的代码，以便您进行比较。
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
public class Test {
private static SecretKey secretKey;
private static KeyPair keyPair;
private static final String STRINGTOENCRYPT = "This is a test";
private static String stringEncripted;
private static byte[] ct;
private static String keyEncripted;
private static byte[] wrapped;
public static final byte[] IV_PARAM = {0x00, 0x01, 0x02, 0x03,
0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0A, 0x0B,
0x0C, 0x0D, 0x0E, 0x0F};
public static void main(String[] args) {
generateKeys();
}
private static void generateKeys() {
secretKey = generateSecretKey(128);
keyPair = generateKeyPair(512);
stringEncripted = encriptString(STRINGTOENCRYPT);
keyEncripted = encriptKey(keyPair.getPublic());
decryptString();
}
private static void decryptString() {
Cipher cipher = null;
Key keyDecrypted = null;
try {
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.UNWRAP_MODE, keyPair.getPrivate());
// keyDecrypted = cipher.unwrap(keyEncripted.getBytes(), "AES", Cipher.SECRET_KEY);
keyDecrypted = cipher.unwrap(wrapped, "AES", Cipher.SECRET_KEY);
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec iv = new IvParameterSpec(IV_PARAM);
cipher.init(Cipher.DECRYPT_MODE, keyDecrypted, iv);
byte[] stringDecryptedBytes = cipher.doFinal(ct);
String stringDecrypted = new String(stringDecryptedBytes);
System.out.println(stringDecrypted);
} catch (Exception e) {
e.printStackTrace();
}
}
private static KeyPair generateKeyPair(int lenght) {
KeyPair keyPublicAndPrivate = null;
try {
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(lenght);
keyPublicAndPrivate = keyGen.genKeyPair();
} catch (Exception ex) {
ex.printStackTrace();
}
return keyPublicAndPrivate;
}
private static SecretKey generateSecretKey(int lenght) {
SecretKey sKey = null;
if ((lenght == 128) || (lenght == 192) || (lenght == 256)) {
try {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
kgen.init(lenght);
sKey = kgen.generateKey();
} catch (NoSuchAlgorithmException ex) {
ex.printStackTrace();
}
}
return sKey;
}
private static String encriptString(String stringtoencrypt) {
byte[] stringtoencryptBytes = stringtoencrypt.getBytes();
Cipher cipher = null;
String stringEncrypted = null;
try {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec iv = new IvParameterSpec(IV_PARAM);
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
// byte[] stringEncryptedBytes = cipher.doFinal(stringtoencryptBytes);
ct = cipher.doFinal(stringtoencryptBytes);
stringEncrypted = new String(cipher.doFinal(stringtoencryptBytes), "UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return stringEncrypted;
}
private static String encriptKey(PublicKey aPublic) {
String keyEncryptedString = null;
try {
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.WRAP_MODE, aPublic);
// byte[] keyEncriptedBytes = cipher.wrap(secretKey);
// keyEncryptedString = new String(keyEncriptedBytes, "UTF-8");
wrapped = cipher.wrap(secretKey);
} catch (Exception e) {
e.printStackTrace();
}
return keyEncryptedString;
}
}
请注意，PKCS#1 填充(RSA 加密)和 CBC 都容易受到填充 oracle 攻击。您可能希望对 AES 使用 RSA/OAEP 和 GCM 模式。
关于java - 使用 RSA 和另一个 key 加密消息，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49710896/